Permanent heat activated transfer printing process and composition

ABSTRACT

An image is printed on a medium by means of a computer driven printer using an ink composition comprising heat activated dye solids, without activating the dye solids during the process of printing onto the medium. The image is transferred from the medium to the object on which the image is to permanently appear by applying sufficient heat and pressure to the medium to activate the dye and transfer the image to the object. The liquid form of the ink composition uses a liquid carrier and an emulsifying enforcing agent which has an affinity for the dye. The emulsifying enforcing agent shields the heat activated dye both prior to, and during, the printing process.

This application is a continuation-in-part of application Ser. No.08/506,894, Jul. 25, 1995, which is a continuation-in-part of Ser. No.08/299,736, Sept. 1, 1994, Pat. No. 5,488,907, which is acontinuation-in-part of Ser. No. 08/195,851, Feb. 10, 1994, U.S. Pat.No. 5,431,501, which is a continuation-in-part of Ser. No. 724,610, Jul.2, 1991, U.S. Pat. No. 5,302,223, which is a continuation-in-part ofSer. No. 549,600, Jul. 9, 1990, abandoned. This application is also acontinuation-in-part of Ser. No. 08/207,756, Mar. 8, 1994, U.S. Pat. No.5,487,614, which is a continuation of Ser. No. 08/195,851, Feb. 10,1994, U.S. Pat. No. 5,431,501.

FIELD OF THE INVENTION

This invention relates to printing generally, and is more specificallydirected to a method of printing heat activated ink by means of an inkjet printer onto paper or other printable substrate as a medium, andsubsequently heat activating the ink, thereby transferring the designformed by the ink from the medium to a substrate on which the design isto permanently appear.

BACKGROUND OF THE INVENTION

Words and designs are frequently printed onto clothing and other textilematerials, and other objects. Common means of applying such designs toobjects include the use of silk screens, and mechanically bonded thermaltransfers.

The use of computer technology allows substantially instantaneousprinting of images. For example, video cameras or scanning may be usedto capture an image to a computer. The image may then be printed by anysuitable printing means, including mechanical thermal printers, ink jetprinters and laser printers. These printers will print in multiplecolors.

Color ink jet printers are in common use. Color ink jet printers usecombinations of cyan, yellow and magenta inks or dyes to producemulti-color images.

The primary types of ink jet printers currently in use fall into threecategories: phase change, free flow, and bubble jet. The inks or dyesused in phase change ink jet printing are contained in a solid compoundwhich changes state by the application of heat to liquify the solid,whereupon the ink composition is printed. Free flow and bubble jetprinters use liquid inks, although the actual printing process of freeflow ink jet printers differs from bubble jet printers.

Heat activated transfer ink solids change to a gas at about 400° F., andhave a high affinity for polyester at the activation temperature and alimited affinity for most other materials. Once the gassificationbonding takes place, the ink is permanently printed and highly resistantto change or fading caused by laundry products.

Hale, U.S. Pat. Nos. 5,246,518, 5,248,363 and 5,302,223 disclose the useof thermal printers to produce an image on a medium or transfer sheetwherein the image is comprised of sublimation or other heat activatedinks. The method described in Hale does not activate the ink during theprinting of the medium or transfer sheet.

The process of printing heat sensitive ink solids such as sublimationinks by means of a phase change ink jet printer is similar to theprocess described in Hale, U.S. Pat. Nos. 5,246,518, 5,248,363 and5,302,223. The use of heat by all ink jet printers presents the problemrecognized in the Hale patents of printing heat activated inks in a nonactivated form by means of such printers, since the ink is exposed tohigh temperatures by the printer. Bubble jet printers, for example, heatthe ink during the printing process to around the boiling point of theink solvent, which is typically water. Free flow ink jet printers useheat to form pressure which transports the ink during the printingprocess.

The use of liquid inks, as required by free flow and bubble jetprinters, presents a new set of problems when trying to print inksolids. The orifices or nozzles of free flow and bubble jet printers arenot designed for the dispensing of solids contained within a liquidmaterial. The orifices of these printers are typically 5-10 microns indiameter, and clogging of the orifice will occur when ink solids oflarge particle size or in high volume are transferred through theorifice.

Further, when the ink solids are placed into the liquid, the ink solidstend to separate from the liquid over time and fall to the bottom of theink container. The ink composition is typically sealed in a container ata manufacturing facility, for subsequent mounting of the containerwithin the ink jet printer, meaning that a substantial storage time forthe ink composition exists prior to use. Separation of the liquid andsolids within the ink formulation presents problems with regard to themechanical operation of the printer and the print quality achieved fromuse of the ink formulation. Materials which inhibit separation must alsoinhibit agglomeration of the solid dye particles, while allowing, andnot preventing due to insulation or otherwise, activation of the ink ordye during the final printing at elevated temperatures.

SUMMARY OF THE PRESENT INVENTION

The present invention is a method of printing heat activated ink solidsin a non activated form onto a medium in a desired image by means of anink jet printer, for subsequent transfer of the image from the medium byheat activation of the ink solids. The invention includes ink or dyecompositions comprising heat activated ink or dye solids for use withthe method. The ink compositions presented include solid compositions atambient temperature for use with phase change ink jet printers, andemulsions or colloids for use with free flow and bubble jet printers.

The ink solids are transferred in the desired design by means of aprinter onto a substrate, which acts as a medium. The substrate may bepaper, or it may be other material which will facilitate and withstandthe transfer temperature, and which facilitates bonding of the ink layerto the substrate.

The ink jet printer incorporates a thermal process, but the ink solidsof the invention do not activate at the operational temperatures of theprinter. Heat activation of the ink solids does not take place at thetime of printing of the image by the printer, but rather, takes place atthe time of the transfer of the image from the medium to the substrateon which the image is permanently applied. The non activated ink solidsproduce a printed image on the medium which is recognizable, but thecolors are dull and are not acceptable for most applications.

Sufficient temperature is then applied to the image to transfer theimage from the medium to the substrate on which the image is topermanently appear. The heat activates, or sublimates, the ink solidsduring this transfer from the medium to the substrate. The image is thenpermanently bonded to the substrate. The permanent image is sharp, withvivid colors forming the image.

When the ink formulation prepared according to the invention is aliquid, finely divided dye solids are present in a liquid carrier, in acolloidal or emulsion form. An emulsifying enforcing agent, which hascharacteristics of a surfactant, surrounds and shields the dye particlesto prevent undesired activation at low heat and to prevent agglomerationof the dye particles. However, the emulsifying enforcing agent allowsactivation of the dye at higher temperatures.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the printing process.

FIG. 2 illustrates an example of a design printed by a printer using theprinting process.

FIG. 3 is a diagrammatic illustration showing exemplary elements ofcomputer and printing systems which could be used to achieve theprinting process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In the preferred embodiment, a video camera or scanning device 2 is usedto capture an image 3. The image is then input into a computer 4. Thecomputer directs a printer 6 to print the image. Any means of formingthe an image which may be printed from a computer may be used, includingimages generated by software. Available computer design graphic softwaremay be used, or still photography may be used. The design may bephotographic, graphic artistic, or simply letters or words. The use ofcyan, yellow and magenta ink compositions allow the printer to print infull color or multi-color designs.

In the present invention, heat activated ink solids are used, and aretransferred to a medium by the printer without activating the inksolids. The heat activated ink solids are transferred onto the medium bythe printer.

Virtually any material may be used as a medium which can be printed uponby a printer, and which will withstand the heat activated transfertemperature of approximately 400° F., as described herein. This mediummay be any paper commonly used with color ink jet printers, however,standard bond paper may be used, or even a sheet of metal, if the metalcan be handled by the printer.

Once the image is printed onto the medium, the image may be permanentlytransferred onto the substrate presently, or at a later time. Mostcommonly, the design will be transferred onto a textile substrate, suchas a shirt 8, although the image may be transferred onto other materialswhich act as a substrate, such as metal, ceramic, wood, or plastic. Thedesign 3, which is printed onto the medium 9 without activating the ink,is placed against the object 8. A temperature which is sufficient toactivate the ink solids is then applied. This temperature will typicallybe around 400° F. This temperature is applied for a time sufficient toheat activate and transfer the ink solids. A heat transfer machine 10may be used to accomplish the transfer of the inks from the medium tothe substrate. Activation, or sublimation, does not take place at thetime of printing the image onto the medium, even though heat may be usedto accomplish the printing of the image onto the medium, but occursduring the transfer from the medium to the substrate.

Phase change ink jet printers use an ink composition which is solid atambient temperature. The ink composition may be in a solid stick form.This "ink stick" comprises heat activated inks, and a phase changematerial, or transfer vehicle, which will liquify upon the applicationof heat to the ink composition. A polymer binder and additives may beadded to the ink composition. The additives may be used to controlmelting, flow, drying, corrosion and other variables. The composition ischanged from solid to liquid by melting the ink stick in a controlledfashion, to apply the ink solids to the medium, and achieve printing.The melted ink composition is contained in a liquid form in a reservoirat the necessary elevated temperature to maintain the ink composition inliquid form. The liquified ink composition is then taken from thereservoir and printed on demand. The ink composition may be present inthe printer in three or more colors, such as cyan, yellow and magenta,and applied by the printer in combination to achieve multiple color orfull color printing.

The transfer vehicle may be a wax or wax like material, such as acertain polymers having a low molecular weight and low melting point.Since wax and wax like materials in liquid form tend to have an affinityfor paper, the transfer vehicle will readily bond with the paper medium,holding the ink solids to the medium, until the ink solids are releasedby the application of heat which is sufficient to activate and transferthe ink solids.

The formulation for an ink composition used with a phase change ink jetprinter is as follows:

    ______________________________________                                        Material                Weight %                                              ______________________________________                                        Heat Activated Dye/Ink Solid                                                                          5-30                                                  Transfer Vehicle        20-70                                                 Emulsifying Enforcing Agent                                                                           1-20                                                  Binder                  0-30                                                  Plasticizer             0-15                                                  Foam Control Agent      0-10                                                  Viscosity Control Agent 0-10                                                  Surface Tension Control Agent                                                                         0-10                                                  Diffusion Control Agent 0-10                                                  Flow Control Agent      0-15                                                  Corrosion Control Agent 0-10                                                  Antioxidant             0-5                                                   TOTAL                   100%                                                  ______________________________________                                    

The heat sensitive or heat activated dye or ink solid may be asublimation ink which is finely divided. It is preferred that the solidparticle have a diameter which is no larger than 0.1 micron. Thetransfer material is a wax or wax like material which liquifies at atemperature of 70 to 120 degrees C to allow printing of the ink onto themedium.

The emulsifying enforcing agent acts as a dispersing agent through whichthe ink solids are distributed. The emulsifying enforcing agent may beone or more polymers or surfactants, which should be anionic. The bindermay be a polymer which strengthens the ink stick when the ink stick isin solid form. The plasticizer increases the solubility of the ink forformulation of the ink stick. The foam control agent and viscositycontrol agent aid in formulating the ink stick.

The surface tension control agent may be a surfactant. This agent aidsin printing of the ink formulation. The diffusion control agent helpscontrol the diffusion of the ink as it is applied to the medium. Theflow control agent helps control the melting temperature and rate of theink during the printing process.

FORMULATION EXAMPLE#1: Cyan phase-change ink-Jet Ink Formula

    ______________________________________                                        Material               Weight %                                               ______________________________________                                        Sublaprint ® Blue 70014.sup.1                                                                    10.0                                                   Polywax ® PE500.sup.2                                                                            10.0                                                   Exxon FN ® 3505.sup.3                                                                            58.0                                                   DisperByk ® 182.sup.4                                                                            0.5                                                    Vinnapas ® B1.5.sup.5                                                                            1.5                                                    Piccolastic ® A25.sup.6                                                                          10.0                                                   Polygard ®.sup.7   5.0                                                    Dibutyl Phthalate      5.0                                                    Total:                 100.0                                                  ______________________________________                                         .sup.1 Keystone Aniline Corporation                                           .sup.2 Petrolite Corp.                                                        .sup.3 Exxon Chemical Co.                                                     .sup.4 BYKChemie, USA                                                         .sup.5 Wacker Chemicals (USA)                                                 .sup.6 Hercules Inc.                                                          .sup.7 Uniroyal Chemical Co.                                             

Polywax PE500 is a transfer vehicle. This transfer vehicle is a wax-likepolymer material. Exxon FN 3505 is a hydrocarbon wax used as part of thetransfer vehicle. Other waxes or combinations could be used as thetransfer vehicle depending on the printer, its operation temperature,the ink to be printed and the medium to be printed.

DisperByk 182 is an emulsifying enforcing agent. An anionic emulsifyingenforcing agent should be used. DispersByk is a polymer type surfactant.Vinnapas B1.5 and Piccolastic are used as binders. Polygard is anantioxidant which is used for corrosion control. Dibutyl phthalate is aplasticizer.

Free flow ink jet printers and bubble jet ink jet printers use inkswhich are in a liquid form. Free flow ink jet printers dispense inkthrough an orifice in an ink container. The printer commands andcontrols the flow of ink through the orifice to print in the desiredmanner.

Bubble jet printers also use inks which are in a liquid form, and whichare held in a container. Bubble jet printers use a different orifice ornozzle system than free flow printers. A channel and heating system isused to form a bubble. The formation of the bubble is controlled by theprinter by the application of heat to the ink to print as desired.

The heat activated inks or dyes are solid particles. Free flow andbubble jet printers are designed to be used with liquid inks, but notwith inks having solid particulate within the liquid. The presence ofsolid material clogs the orifice or nozzle of the printer. Further,liquid ink compositions into which a solid particulate is placed ordissolved are not homogenous over time. The solid ink particles in themixture settle from the liquid toward the bottom of the ink container.This settling increases the clogging of the orifice. Further, printquality is affected if the ink is not consistent.

The liquid ink composition of the present invention is an emulsioncomprised of finely divided heat activated ink solids which are placedin an emulsion by means of an emulsifying enforcing agent which ispresent in a solvent. Humectants, corrosion inhibitors, surfactants, andanti-foaming agents may also be included in the composition.

The formulation of an emulsion comprising heat activated ink solidswhich is used with ink jet printers requiring liquid inks is as follows:

    ______________________________________                                        Material                Weight %                                              ______________________________________                                        Heat Activated Dye/Ink Solid                                                                          5-30                                                  Emulsifying Enforcing Agent                                                                           1-20                                                  Binder                  0-30                                                  Humectants              0-40                                                  Foam Control Agent      0-10                                                  Fungicide               0-2                                                   Viscosity Control Agent 0-10                                                  Surface Tension Control Agent                                                                         0-10                                                  Diffusion Control Agent 0-10                                                  Flow Control Agent      0-15                                                  Evaporation Control Agent                                                                             0-20                                                  Corrosion Control Agent 0-10                                                  Cosolvent               0-30                                                  Solvent                 30-90                                                 TOTAL                   100%                                                  ______________________________________                                    

The heat activated dye or ink solid is finely divided and placed into anemulsion by means of the emulsifying agent and the solvent, which may bewater. The remaining agents may be added to facilitate formulation,storage and/or printing of the liquid ink composition.

FORMULATION EXAMPLE#2-Yellow Ink-Jet Formula

    ______________________________________                                        Material               Weight %                                               ______________________________________                                        Bafixan ® Yellow 3FE.sup.8                                                                       2.0                                                    Dipropylene Glycol     4.5                                                    DMSO                   1.5                                                    Cobratec ®.sup.9   0.45                                                   NaOH (10N)             3.0                                                    Distilled H.sub.2 O    88.55                                                  Total:                 100                                                    ______________________________________                                         .sup.8 BASF Corporation                                                       .sup.9 PMC Specialties Group                                             

Formulation Example 2 comprises a heat activated yellow ink solid ordye. Dipropylene glycol and DMSO are co-solvents. Sodium Hydroxide is aninorganic emulsifying enforcing agent, which also acts as a fungicide.Distilled water acts as a solvent. Cobratec® acts as a corrosioninhibitor.

In this formulation, a particular ink solid is finely divided to yield asmall particle size. The particular ink solid of Example 2 will tend tosubstantially dissolve within sodium hydroxide, which is used as theemulsifying enforcing agent. The combination of the sodium hydroxide andthe solvent, which is the formulation example is distilled water, yieldan emulsion which may be used in bubble jet and free flow ink jetprinters.

Generically, a "humectant" is a moisturizing agent. In the relevant art,the term "humectant" is used to describe agents which are included inink formulations to regulate the rate at which the ink dries and tocontrol the viscosity of the ink. In addition to these properties, thepresent invention may comprise one or more humectants which will preventclogging of the orifice or nozzle. With certain inks, the humectantswill regulate the sublimation rate of the inks or dyes as they aretransferred from the medium to the object on which the printed design isto permanently appear. The humectant in formulation example 2 isdipropylene glycol, which acts as a co-solvent and humectant.

FORMULATION EXAMPLE#3; Cyan Ink-Jet Formula

    ______________________________________                                        Material               Weight %                                               ______________________________________                                        Sublaprint ® Blue 70013.sup.10                                                                   1.0                                                    Lignosol ® FTA.sup.11                                                                            3.5                                                    ME ® 39235.sup.12  10.0                                                   Diethylene Glycol      9.5                                                    DMSO                   1.0                                                    Distilled H.sub.2 O    75.0                                                   Total:                 100.00                                                 ______________________________________                                         .sup.10 Keystone Aniline Corporation                                          .sup.11 Lignotech (U.S.) Inc.                                                 .sup.12 Michelman, Inc.                                                  

Sublaprint® Blue 70013 is a heat activated ink or dye solid. Lignosol®FTA and ME®39235 are emulsifying enforcing agents. Lignosol® FTA alsoacts as a fungicide. ME®39235 is a polymer, and more specifically, it isa polyethylene binder. Diethylene Glycol and DMSO act as humectants. Thesolvent is distilled water.

Sublaprint® Blue 70013 is more difficult to sublimate than Bifaxan®Yellow 3GE, and is less soluble in the emulsifying enforcing agent.Diethylene glycol is used as a humectant to facilitate sublimation ofthe Sublaprint® Blue ink solid.

The heat activated ink solid is finely divided to a small particle size.The finely divided ink solid is combined with one or more emulsifyingenforcing agents, which are in turn combined with the solvent.

Formulation Example#4: Magenta Ink-Jet Ink Formula

    ______________________________________                                        Material                Weight %                                              ______________________________________                                        Intratherm ® Brill Red P-31NT.sup.13                                                              .5                                                    Lignosol ® FTA.sup.14                                                                             3.0                                                   ME ® 39235.sup.15   11.0                                                  NA-SUL ®.sup.16     1.0                                                   DeeFo ® 806-102.sup.17                                                                            0.2                                                   Sorbitol                0.5                                                   Dipropylene Glycol      3.5                                                   Distilled H.sub.2 O     79.3                                                  Total:                  100                                                   ______________________________________                                         .sup.13 Crompton & Knowles Corporation                                        .sup.14 Lignotech (U.S.) Inc.                                                 .sup.15 Michelman, Inc.                                                       .sup.16 King Industries                                                       .sup.17 Ultra Additives                                                  

Formulation Example#4 comprises a heat activated ink solid or dye whichis finely divided and combined in an emulsifying enforcing agent. Theemulsifying enforcing agent or medium is, as with Example#3, Lignosol®FTA and ME® 39235. Distilled water is used as a solvent. DipropyleneGlycol is used as a humectant.

Formulation Example#4 further comprises an anti-foaming or foamingcontrol agent, DeeFo® 806-102 to retard foaming of the liquid inkcomposition. Formulation Example#4 further comprises a surfactant, whichmay be Sorbitol®, and a corrosion inhibitor, which, in this example, isNA-SUL®.

Formulation Examples 2, 3 and 4 are emulsions. In Example 2, theparticular dye has a tendency to dissolve in the emulsifying enforcingagent. Formulation Examples 3 and 4 may also be described as colloids,having finely divided ink particles of not larger than 0.1 microns indiameter present within the disperse medium.

The invention provides an emulsion or colloid which will work withinfree flow ink jet printers, piezio electric printers, and bubble jetprinters, without experiencing problems relating to orifice cloggingwhich results from the use of an ink solid. Further, the use of anemulsion or colloid prevents the separation of the ink solids from theliquid components, rendering an ink composition which is stable overtime. Typically, the liquid ink formulations are present within theprinters in containers. Three or more colors of liquid ink are present.The containers may be factory sealed, and as such, the ink formulationmay be held within the container for a long period of time.

The bubble jet printer forms the bubble which is used to print the inkat approximately the boiling point of the ink solvent. In mostformulations, water will be used as the solvent, so that the ink isexposed to temperatures of 100 degrees C or higher as the ink isprinted. Comparable temperatures may be used in free flow ink jetprinters to create pressure for the purpose of transporting the ink forprinting. As with the phase change ink jet printer, the ink is exposedto temperatures which will activate or sublimate some heat activatedinks or dyes. The inks or dyes used in the ink compositions herein willnot activate or sublimate at the operational temperatures of theprinter.

The liquid ink formulation comprises a liquid carrier. The liquidcarrier, or solvent, may be water. An emulsifying enforcing agent, whichis soluable in the liquid carrier, forms an emulsion or a colloid in theliquid carrier. The emulsifying enforcing agent has an affinity for theheat activated dye, and attaches to, or may surround, all or part ofindividual particles of the dye particles.

The heat activated dye as used is a finely divided solid which issubstantially insoluable in the liquid carrier. The dye particles, whenplaced in a liquid, will tend to agglomerate, vastly reducing, andpractically eliminating, the efficacy of the ink formulation. Theemulsifying enforcing agent is used to form an emulsion or a colloid,and in the present invention, also surrounds and shields, and therebyseparates, the individual dye particles from the liquid carrier and fromeach other, preventing agglomeration of the dye particles, and therebypreventing the ink formulation from clogging the orifices of theprinter, such as the ink jets. The emulsifying enforcing agent shieldsand insulates the dye particles, preventing activation or sublimation ofthe dye due to exposure to heat present in the printer and the printerprocesses. The emulsifying enforcing agent shields the dye particles,and improves the shelf life of the ink formulation. The adverse effectsof heat, chemical reactions, light, time, and other factors that may bepresent in the packaging environment, or any environment within orsurrounding the printer, or printing processes are eliminated or reducedby the emulsifying enforcing agent. However, while the emulsifyingenforcing agent shields the dye particles, the insulation properties ofthe emulsifying enforcing agent are such that heat activation of theheat activated dye is achieved during final transfer of the image fromthe medium, which is performed at, or above, the temperature at whichthe dye activates, and the required optical density of the dye afterfinal transfer by heat activation is attained.

An example of an emulsifying enforcing agent which will achieve theobjects of the invention, when used with water as a liquid carrier, is ametallic sulfonate salt known as lignin sulfonate. Lignin sulfonates aresold under various brand names, including Lignosol and Raykrome. Otherlignin products which may be used as the emulsifying enforcing agent toproduce stable dispersion/emulsion systems include kraft lignin productsand oxylignins.

Generally, lignin materials may be categorized by the two main processesin manufacturing lignins: kraft pulping and sulfite pulping. Each of theprocesses produce lignin materials with different structures andmolecular weights, and therefore, they exhibit different performanceproperties in dye dispersing, stablizing and emulsification. Other thanthese two groups, there is a group of lignin products called oxyligninswhich are derived from lignins that have been oxidized and have areduced number of sulphonic and methoxyl gruops and increased number offunctional phenolic, hydroxyl and carboxylic groups.

Lignin products can be further modified through processes or reverseprocesses of sulphoncation, methylation, carboxylation andfractionation, etc. in order to change their chemical and physicalproperties, such as water solubilities in different pH ranges, molecularweight, heat stability and emulsification ability.

Lignin sulphonates, kraft lignins, or oxylignins can be used as dyedispersant/emulsifying enforcing agents in the invention to generatestable sublimation or heat sensitive dye emulsion/colloid systems, withproper adjustment of solvent and usage level. Lignosulfonate productssuch as Maprasperse CBA-1 (Lignotech), Marasperse 52CP (Lignotech),Lignosol FTA (Lignotech), Lignosol SFX-65 (Lignotech), Temsperse S002(Temfibre, Inc.) Stepsperse DF series (Stephan Co.), and Weschem NA-4(Wesco Technologies, LTD) may be used. Kraft lignin products such asDiwatex XP (Lignotech), and Reax 85 (Westvaco), and oxylignin productssuch as Marasperse CBOS-6 and Vanisperse CB are suitable for use as theemulsifying enforcing agent in the ink formulation of the presentinvention. The resulting aqueous system forms a double-layer structure,with a dye particle in the center surrounded by lignin molecules andanother hydrated layer on the outer layer, to shield the dye particlesfrom reagglomerating, and from the effects of chemical and physicalchanges introduced during storage or printing of the ink formulation.

Other materials can be used as either emulsifying enforcing agents or asadditives to improve the emulsion/colloid stability, and therebyenchance the printing quality, by eliminating clogging and kogation atthe print head. These materials may comprise a concentration from 0.1%to 15% by weight of the total formulation without damaging thesublimation heat transfer quality of the heat-sensitive dye at the heattransfer stage. These materials can be added into the system during theprocess of reducing the particle size of the dyes, or after the dyeparticles have been dispersed into the aqueous solution. These materialsfunction also as emulsion/colloid stablizers, leveling agents, wettingagents, or foam control agents.

The materials which can be used for this purpose incude alkylarylpolyether alcohol nonionic surfactants, such as Triton X series(Octylphenoxy-polyethoxyethanol); alkylamine ethoxylates nonionicsurfactants such as Triton FW series, Triton CF-10, and Tergitol (UnionCarbide Chemicals); polysorbate products such as Tween (ICI Chemicalsand Polymers); polyalkylene and polyalkylene modified surfactants, suchas Silwet surfactants (polydimethylsioxane copolymers) and CoatOSilsurfactants from OSI Specialties; alcohol alkoxylates nonionicsurfactants, such as Renex, BRIJ, and Ukanil; Sorbitan ester productssuch as Span and Arlacel; alkoxylated esters/PEG products, such asTween, Atlas, Myrj and Cirrasol surfactants from ICI Chemicals andPolymers; unsaturated alcohol products such as surfynol seriessurfactants from Air Products Co., alkyl phosphoric acid estersurfactant products, such as amyl acid phosphate, Chemphos TR-421; alkylamine oxide such as Chemoxide series from Chemron Corporation; anionicsarcosinate surfactants such as Hamposyl series from Hampshire Chemicalcorporation; glycerol esters or polyglycol ester nonionic surfactantssuch Hodag series from Calgene Chemical, Alphenate (Henkel-Nopco),Solegal W (Hoechst AG), Emultex (Auschem SPA); and polyethylene glycolether surfactants such as Newkalgen from Takemoto Oil and Fat Co.

The solid dyes which are used in the ink formulation and in the printingprocess have a particle size which is too large for use in ink jetprinters, as such dyes are currently commercially available. Theparticle size and nonsolubility in water also presents other problemspreviously discussed. The dye must be finely divided, which may beaccomplished using mills, grinders, homogenizers or micronizers. One ormore different emulsion enforcing agents including surfactantsdispersants, emulsifying agents, wetting agents, defoamers oranti-foamers, or corrosion inhibitors may be used in the process toimprove and facilitate the process of finely dividing the dye. Examplesof grinding devices to finely divide the dye include microfluidizers,roller mills, vertical mills, horizontal mills, jet mills, ball mills,attrition mills, and ultrasonic micronizer/homogenizing mills.

For example, the heat sensitive dye is mixed with the emulsifyingenforcing agent, and/or other additives and co-solvents, and deionizeddistilled water. The dry chemicals are mechanically mixed, dispersedinto the liquid phase, and then fed into grinding facility. The grindingdevice is operated while monitoring temperature, pressure, viscosity,interfacial tension, surface tension, pH value and flow speed, withoutactivating the heat sensitive dye, until the mean diameter of the dyeparticles is between 0.1 to 0.5 microns.

Particles which have a diameter of larger than 0.2-0.5 microns should beeliminated from the composition, such as by filtration or centrifuge.The resulting ink composition has a mean particle size of 0.2 microns orless, with the solid percentage ranging from 0.05% -10% by weight, toproduce an ink composition which achieves the objectives of the presentinvention.

What is claimed is:
 1. A method of printing using heat activated dyesolids by means of a printer which uses liquid ink, comprising the stepsof:a. preparing a liquid ink formulation comprising a heat activateddye, a liquid carrier, and an emulsifying enforcing agent which issoluble in said liquid carrier and has an affinity for said heatactivated dye and surrounds individual particles of said heat activateddye and separates said individual particles from said liquid carrier,and which allows heat activation of said heat activated dye at thetemperature at which said heat activated dye activates, and wherein saidheat activated dye is a finely divided solid which is substantiallyinsoluble in said liquid carrier; b. supplying a printer with saidliquid ink formulation; c. printing said liquid ink formulation in adesired image by means of said printer onto a medium at a temperaturewhich is below the temperature at which said heat activated dyeactivates; and d. transferring said image from said medium to an objecton which the image is to appear by thermal means at a temperature whichis sufficient to activate the heat activated dye, so as to cause theheat activated dye to transfer onto said object.
 2. A method of printingusing heat activated dye solids by means of a printer which uses liquidink as described in claim 1, wherein said emulsifying enforcing agent isa lignin.
 3. A method of printing using heat activated dye solids bymeans of a printer which uses liquid ink as described in claim 1,wherein said liquid ink formulation further comprises an additive.
 4. Amethod of printing using heat activated dye solids by means of a printerwhich uses liquid ink as described in claim 3, wherein said additive isa surfactant.
 5. A method of printing using heat activated dye solids bymeans of a printer which uses liquid ink as described in claim 2,wherein the emulsifying enforcing agent is a sulphonated lignin.
 6. Amethod of printing using heat activated dye solids by means of a printerwhich uses liquid ink as described in claim 1, wherein said printer is apiezo electric printer.
 7. A method of printing a design by means of acomputer driven printer using heat activated dye solids, comprising thesteps of:a. preparing an ink formulation comprising a heat activateddye, a liquid carrier, and an emulsifying enforcing agent which issoluble in said liquid carrier and has an affinity for said heatactivated dye, wherein said emulsifying enforcing agent surrounds andshields individual particles of said heat activated dye and separatessaid individual particles from said liquid carrier, and wherein saidheat activated dye is a finely divided solid which is substantiallyinsoluble in said liquid carrier; b. supplying a printer with said inkformulation; c. printing said ink formulation in a desired image bymeans of said printer onto a medium at a temperature which is below thetemperature at which said heat activated dye activates; and d.transferring said image from said medium to an object on which the imageis to appear by thermal means at a temperature which is sufficient toactivate the heat activated dye, so as to cause the heat activated dyeto transfer onto said object.
 8. A method of printing a design by meansof a computer driven printer using heat activated dye solids asdescribed in claim 7, wherein the emulsifying enforcing agent is asulphonated lignin.
 9. A method of printing a design by means of acomputer driven printer using heat activated dye solids as described inclaim 8, wherein the emulsifying enforcing agent is Lignosol.
 10. Amethod of printing a design by means of a computer driven printer usingheat activated dye solids as described in claim 7, wherein said printeris a piezo electric printer.